Etiology, Pathogenesis, and Natural History of Idiopathic CD4+ Lymphocytopenia

Study Summary

Background: * Idiopathic CD4+ lymphocytopenia (ICL) is a condition in which there is a decreased level of CD4+ lymphocytes (a type of white blood cell), which can lead to opportunistic infections or autoimmune disorders and diseases. Objectives: * To characterize the natural history with regard to CD4+ T cell count and onset of infection, malignancy, and autoimmunity. * To describe the immunological status of patients affected by ICL while providing the best possible standard therapy to eradicate opportunistic infections. * To establish the timeline of CD4 lymphocytopenia, with particular focus on defining subgroups of patients according to the decline, stabilization, or rise of CD4+ T cell counts over time. * To characterize the opportunistic infections that occur in ICL patients at microbiologic and molecular levels. * To characterize the immunophenotype and possible genetic immunodeficiency causes of ICL. * To determine whether measurable immunologic parameters correlate with the development of opportunistic infections or other comorbidities such as lymphoma in patients with ICL. * To determine whether there is any association between ICL and autoimmunity. * To determine CD4+ T cell turnover, survival, functionality, and cytokine responsiveness in ICL patients. Eligibility: * Patients 2 years of age and older with an absolute CD4 count less than 300 in children 6 years or older and adults or less than 20% of T cells in children younger than 6 on two occasions at least 6 weeks apart. * Patients with negative results of HIV testing by ELISA, Western Blot, and viral load. * Patients must not have underlying immunodeficiency conditions, be receiving cytotoxic chemotherapy (anti-cancer drugs that kill cells), or have cancer. Design: * At the initial visit to the National Institutes of Health, the following evaluations will be conducted: * Personal and family medical histories. * Physical examination, including rheumatology evaluation and other consultations as

Primary Outcome

To further characterize the natural history of ICL while also investigating the genetic, environmental, and immunologic features of the condition.

Conditions Studied

Study Locations (1)